1) you can take search in HC records and find out whether case is settled or not 

2) then decide your next course of action 

3) you can file intervenor application in HC 

Is the building under repair board of Mhada?

The landlord is an individual or are there co owners?

Ask the landlord to give the high court case number. Status can checked from Bombay high court website 

Also ask the builder under which provision of DC rules he proposes to redevelop the property

Is the redevelopment proposed through a builder?

All these questions need to be answered before I can give a substantive reply

Yes tenant of chawl can make application in High court to make them necessary party in the suit. 

Yes you can file a writ petition separately or intervene in the same

If  you know with whom the owner dispute was going on in the high court related to this chawal property. 

You can get MoU signed by all those family members of owner and mention all history..  Family tree and property history,  so you people will not have any trouble and secondly you will come to know if builder is telling truth or false of case settlement outside court. 

Don't move application outside high court this matter,  instead you people make repair in the chawal by taking BMC permission. 

1.  Yes, as interested parties, you can move "intervene application" in the existing case, by providing proper reasons and documentary evidences.

2. Once application is accepted, THEN nothing will move without hearing your side.

3.  Consent letter is a mere letter having no legally enforceable value.  The important thing is the "Development Agreement" (DA), with proper strategic clauses.

No reliability of oral commitment. Dispute is of civil nature and between family members, Tenants have no locus standi to become party.

Whenever go for redevelopment, execute MOU of conditions.

- If, you will give the Pagadi chawl , then there is possibility to disposses by the said landlord, after re-development.

- You should not trust on oral talkings of the landlord regarding the suit before the High Court. 

- Since, you are in possession of the Chawl , so you can intervene in the pending case after moving an application for the same .

- You can enquire from the website of High court or physically visiting the court personally , for getting the details of the said case. But it is advised take help of any local lawyer.

- Further, if the landlord try to disposses you forcibly , then you should file an injuction suit , without mentioning the High court details, as you are in dark for that case. 

vacant rooms and shops would be considered for 51 per cent majority 

the vacant rooms and shops which are in lock and key of landlord will be counted as 1 tenant

if there are tenants who occupy more than one unit in the building then despite that the tenant's vote will be counted as 1 only

in such manner as above the 51% majority is to be ascertained

vacant shops and rooms considered for 51%  majority. 

As you said that this was a family dispute among the landlord and his family members, hence as a tenant you do not have any rights to interfere in the court matter which is a family dispute for them.

You are all not a party to that case.

You may have to wait for the matter to be settled by court and then go for the redevelopment.

Any step taken in haste will prove fatal to your efforts and your very entitlement.

As per the latest notification by the Brihanmumbai Municipal Corporation (BMC), all pagdi tenants living in non-cessed buildings before June 1996, would now be eligible for new flats in the redeveloped buildings. The rule will be applicable in case the tenant transfers the flat in the name of another person. The occupant will also be eligible for accommodation after the redevelopment.

The pagdi system is a rental model where the landlord is the owner of the property, but the possession is retained with tenants by paying a nominal rent. Officials have shared that most of the non-cessed buildings are situated in the suburbs and many of them are in dilapidated condition.

The Mumbai Development Control and Promotion Regulations 2034 (DCPR) encourages the redevelopment of buildings working on pagdi system by offering attractive incentives to landlords. The incentives are provided based on the total area required to rehabilitate the existing occupants.

The rules further read that the tenants are entitled to a minimum area of 300 sq ft and a maximum area of 1,292 sq ft, free of cost. The tenant needs to pay the construction cost if the property area crosses the maximum cap.

For redevelopment of tenancy properties, there are three parties between which the agreement for redevelopment is done
(1) Owner;
(2) Tenant;
(3) Builder/developer and all other processes are the same as the redevelopment of a co-operative housing society.

Here, the landlord of the property has full right over the sale of the land because of the records of the property i.e. 7/12 extracts and property papers, so the landlord makes the deal with the developer/builder accordingly and the landlord takes the profit out of the property on a permanent basis and the tenants who are in possession of the said room/flat after redevelopment, become the sole owners of the said room/flat

The landowner requires consent of 51% of the total residents .to go for redevelopment and must rehabilitate all the existing tenants in the new structure. ..